1. Field of the Invention
The present general inventive concept relates to an image forming apparatus to form multicolor images using an electro-photographic technique and an image forming method thereof, and more particularly, to a multicolor image forming apparatus in which image degradation caused by developer stress is reduced and thus a life span of the image forming apparatus is increased, and an image forming method thereof.
2. Description of the Related Art
Image forming apparatuses using an electro-photographic technique, for example printers, copy machines, fax machines, or multifunction peripheral (MFP), include a photoconductive medium, an exposure device to scan a laser beam toward the photoconductive medium and to form an electrostatic latent image according to image data, a developing device to supply a developer to the photoconductive medium on which the electrostatic latent image is formed and to develop the electrostatic latent image, and a transferring device to transfer the developed latent image.
There is demand for image forming apparatuses which use an electro-photographic technique, such as printers or copy machines, to have a full-color offering function in order to satisfy various requirements of users. With the development of digital technology, image forming apparatuses using an electro-photographic technique, for example printers, copy machines, or multifunction peripherals, have ensured high quality, and have improved performance so as to satisfy a requirement for properties such as high resolution, excellent color reproducibility, wide color reproduction range, high clarity, and/or proper color gradation.
Multicolor image forming apparatuses which are used to form various colors include dark developers such as yellow, magenta, cyan, and black dark developers, and light developers such as magenta and cyan light developers as developers or toners which are generally used in an image forming unit.
Image forming apparatuses using an electro-photographic technique form color images using developers or toners of four basic colors, such as yellow, magenta, cyan, and black. However, such image forming apparatuses have limitations concerning a resolution, color reproducibility, color clarity, and color gradation of images produced thereby, since it is difficult for particles of a developer or a toner to be uniformly and stably attached to dots formed at regular intervals. In addition, the color gradation corresponding to a ratio of dot density of dots having the developer or the toner disposed thereon to the dot density of dots which do not have the developer or the toner disposed thereon is poor.
Image forming apparatuses using an electro-photographic technique may be effective in printing documents which include text, but it is ineffective for image forming apparatuses which are used to print photos or pictures that require a high resolution, excellent color reproducibility, high clarity, and proper color gradation.
Image forming apparatuses such as an inkjet printer use liquid developers or toners which have approximately 11 or 12 colors, and thus generate an image superior to that of a laser printer in resolution, color reproducibility, clarity, and color gradation.
Multicolor image forming apparatuses consume more light developers than dark developers, and thus the dark developers suffer from greater stress than the light developers, which results in image degradation. The image degradation causes an image to be blurred or causes white stripes to appear.
The image degradation caused by the dark developer makes it impossible for an image forming apparatus to be used for a long period of time.
Therefore, there is a need for image forming apparatuses which may be used for a long period of time without having image degradation.